[Effect of electroacupuncture at different acupoints on plasma TXB2 and 6-keto-PGF(1alpha), contents in dysmenorrhea rats].

Objective: To observe the effect of electroacupuncture (EA) on plasma thromboxane B2(TXB2) and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) levels in dysmenorrhea rats in order to investigate its mechanism underlying relief of primary dysmenorrhea and specificity of acupoint efficacy.

Methods: Female SD rats with diestrus were randomly divided into saline control (control), model, EA Sanyinjiao (SP 6), EA Xuehai (SP 10), EA Xuanzhong (GB 39) and EA non-acupoint (NAP) groups, with 10 rats in each. Dysmenorrhea model was established by subcutaneous injection of Estradiol Benzoate (0.5 mg/rat on the 1st and 10th day, and 0.2 mg/rat from the 2nd to the 9th day) and intraperitoneal injection of Oxytocin (0.2 mL/rat, 1 h after last injection of Estradiol Benzoate on the 10th day). EA was applied to bilateral SP 6, SP 10, GB 39, and non-acupoint (the mid-point between the Gallbladder and Stomach meridian at the GB 39 level) for 20 min. The latency and score of writhing were recorded for 20 min. Plasma TXB2 and 6-keto-PGF1alpha contents were detected by radioimmunoassay.

Results: Compared with the control group, the latency of writhing in the model group was shortened considerably (P < 0.01), and the writhing score was increased significantly (P < 0.01). In comparison with the model group, the writhing latency was increased significantly only in the EA-SP 6 group (P < 0.05), and the writhing scores in the EA-SP 6, EA-SP 10, EA-GB 39 and EA-NAP groups were reduced remarkably (P < 0.01). Plasma TXB2 content and the ratio of TXB2/6-keto-PGF1alpha. were significantly higher in the model group than in the control group (P < 0.01). Compared to the model group, plasma TXB2 levels and the ratios of TXB2/6-keto-PGF1alpha. in the EA-SP 6, EA-SP 10, EA-GB 39 and EA-NAP groups were downregulated markedly (P < 0.05, P < 0.01), while plasma 6-keto-PGF1alpha was upregulated strikingly only in the EA-SP 6 group (P < 0.05). No significant differences were found among the EA-SP 6, EA-SP 10, EA-GB 39 and EA-NAP groups in the writhing latency and writhing score, plasma TXB2 and 6-keto-PGF1alpha, levels (P > 0.05).

Conclusion: EA can relieve pain reaction in dysmenorrhea rats, which may be closely associated with its effects in downregulating plasma TXB2, upregulating plasma 6-keto-PGF1alpha, content, and balancing plasma TXB2/6-keto-PGF1alpha. The effect of EA of SP 6 is relatively better.